1. Field of the Invention
The present invention relates to an apparatus, such as a piston, used to dispense fluids from fluid vessels.
2. Description of Related Art
A method of dispensing fluids from a fluid vessel, such as a tank, may involve the use of a rigid piston disposed inside the tank to drive the fluid therefrom. The rigid piston is pushed through the tank during the dispensing process by the use of pressurized air, nitrogen or any other suitable gas. The piston typically includes annular seal rings that form a seal between the inner surface of the tank and the piston, and which wipe the interior of the tank as the rigid piston is pushed through the tank.
Since the piston is rigid and larger than any orifice provided on the tank, the tank is typically manufactured with the piston installed in the tank. Thus, the rigid piston is actually part of the tank and cannot be removed without dismantling the tank. As such, the rigid piston can only be used in a single, given tank for which it is installed. The rigid piston is also made to be fairly long in order to accommodate spaced apart pads that protrude therefrom and engage the inner surface of the tank, such as that described in U.S. Pat. No. 4,721,235. These pads help to prevent canting as the rigid piston moves through the tank. As such, the rigid piston occupies a large volume of space that could otherwise be used to store fluid.
It would therefore be desirable to provide an apparatus for dispensing a fluid from a fluid vessel that does not possess the above mentioned drawbacks. The present invention provides an apparatus for sealing a portion of a fluid vessel. The apparatus includes an inflatable and collapsible enclosed structure constructed and arranged to transition between an inflated configuration and a collapsed configuration when pressurized fluid is received therein and released therefrom, respectively. The apparatus includes at least one annular seal member protruding from an outer surface of the enclosed structure, wherein the annular seal member is constructed and arranged to engage an inner surface of the fluid vessel to form a fluid tight seal between the inner surface and the outer surface of the enclosed structure when the enclosed structure is disposed therein and pressurized to substantially the inflated configuration.